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Peanut Butter Mississippi Mud Brownies


Peanut Butter Mississippi Mud Brownies are wonderfully rich and gooey with a layer of marshmallows, lots of peanut butter flavor, and a chocolate icing. These brownies really can’t be beat!

Peanut Butter Mississippi Mud Brownies on a cutting board.

Chocolate and peanut butter is maybe my favorite flavor combination ever. (Original I know.) But who doesn’t love it?


I almost feel like adding another ingredient to the mix is like adding a third wheel and upsetting the dynamics of a perfect union. But these Peanut Butter Mississippi Mud Brownies are incredibly rich and gooey, and a layer of marshmallows fits right in without detracting from the delicious flavors of the chocolate and peanut butter.


The creaminess of the peanut butter definitely takes these brownies over the edge and I think I like this recipe even more than the Mississippi Mud Cupcakes I made several weeks ago. But maybe not quite as much as Mississippi Mud Pie. That one is hard to beat!

Brownies in a 9-13-inch baking pan.

Recipe Tips:

Either creamy or crunchy peanut butter can be used.

These brownies can be stored in an airtight container at room temperature for 4 days.

Try These Other Amazing Brownie Recipes:

Peanut Butter Mississippi Mud Brownies on a cutting board.

Love southern desserts? Follow Spicy Southern Kitchen on Pinterest and Instagram for more brownies, pies, and cobblers.

Watch the short video below to see how easy these Peanut Butter Mississippi Mud Brownies are to make.

Peanut Butter Mississippi Mud Brownies on a cutting board.

Peanut Butter Mississippi Mud Brownies

Peanut Butter Mississippi Mud Brownies have a layer of peanut butter, marshmallows, and a rich chocolate icing.
PREP: 10 minutes
COOK: 32 minutes
TOTAL: 42 minutes


  • 4 ounces unsweetened chocolate
  • 2 cups sugar
  • 1 cup butter, softened
  • 4 eggs
  • 1 cup flour
  • 1 teaspoon vanilla extract
  • 2/3 cup semisweet chocolate chips
  • 3 cups mini marshmallows
  • ¾ cup peanut butter
  • 1 teaspoon canola oil
  • ¼ cup butter
  • 3 tablespoons unsweetened cocoa
  • ¼ cup milk
  • 2 cups confectioners' sugar
  • ½ teaspoon vanilla extract


  • Preheat oven to 350°. Chop the chocolate into small pieces, place in a small heavy-bottomed pan and heat over low heat, stirring constantly, until melted. Remove from heat.
  • Using an electric mixer, beat butter and 2 cups sugar at medium speed until light and fluffy. Add eggs one at a time, waiting until each egg is blended in before adding the next one.
  • Add melted chocolate, and beat just until blended. Add flour and 1 teaspoon vanilla extract and beat on low speed until flour is moistened.
  • Spread batter into 9X13-inch pan. Sprinkle semi-sweet chocolate chips on top and bake for 30 minutes if using a metal pan and slightly longer in a glass pyrex dish.
  • Sprinkle marshmallows on top of brownies and return to oven on top rack for 1-2 minutes or until marshmallows are melted and lightly browned on top.
  • Combine peanut butter and canola oil in a small bowl and microwave for 10 seconds on HIGH. Stir to combine and drizzle on top of marshmallow covered brownies.
  • For chocolate frosting, combine ¼ butter, unsweetened cocoa, and milk in a saucepan and cook over medium heat, stirring constantly for 2-3 minutes.. Whisk in powdered sugar and vanilla extract until smooth. Drizzle on top of brownies.


Calories: 514kcal
Course: Dessert
Cuisine: Southern
Keyword: brownies, peanut butter

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Originally published June 8, 2013.

More Mississippi Mud Recipes

Mississippi Mud PieMississippi Mud Pie

Mississippi Mud CupcakesMississippi Mud Cupcakes

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10 thoughts on “Peanut Butter Mississippi Mud Brownies”

  1. Irina @ wandercrush

    Oh goodness gracious, I shouldn’t have clicked this link past midnight! Hahah, now excuse me while I rummage through my fridge.

  2. Julia | JuliasAlbum.com

    These brownies look spectacular! I immediately pinned them and can’t wait to try them!

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